I use radicals for CalDAV and save notes there together with my calendars. On Android there is jtx Board which let’s you work with them. Sadly on Linux I couldn’t find anything so I started writing something myself but don’t have much time to work on it https://github.com/jeena/JNotes
That’s an interesting idea, need to check if they offer some kind of a API for that.
But then there is this other thing, what about dns cache?